1// SPDX-License-Identifier: GPL-2.0-only
 2
 3#include <linux/string.h>
 4
 5#include <drm/drm_drv.h>
 6#include <drm/drm_edid.h>
 7
 8#include "udl_drv.h"
 9#include "udl_edid.h"
10
11static int udl_read_edid_block(void *data, u8 *buf, unsigned int block, size_t len)
12{
13	struct udl_device *udl = data;
14	struct drm_device *dev = &udl->drm;
15	struct usb_device *udev = udl_to_usb_device(udl);
16	u8 *read_buff;
17	int idx, ret;
18	size_t i;
19
20	read_buff = kmalloc(2, GFP_KERNEL);
21	if (!read_buff)
22		return -ENOMEM;
23
24	if (!drm_dev_enter(dev, &idx)) {
25		ret = -ENODEV;
26		goto err_kfree;
27	}
28
29	for (i = 0; i < len; i++) {
30		int bval = (i + block * EDID_LENGTH) << 8;
31
32		ret = usb_control_msg(udev, usb_rcvctrlpipe(udev, 0),
33				      0x02, (0x80 | (0x02 << 5)), bval,
34				      0xA1, read_buff, 2, USB_CTRL_GET_TIMEOUT);
35		if (ret < 0) {
36			drm_err(dev, "Read EDID byte %zu failed err %x\n", i, ret);
37			goto err_drm_dev_exit;
38		} else if (ret < 1) {
39			ret = -EIO;
40			drm_err(dev, "Read EDID byte %zu failed\n", i);
41			goto err_drm_dev_exit;
42		}
43
44		buf[i] = read_buff[1];
45	}
46
47	drm_dev_exit(idx);
48	kfree(read_buff);
49
50	return 0;
51
52err_drm_dev_exit:
53	drm_dev_exit(idx);
54err_kfree:
55	kfree(read_buff);
56	return ret;
57}
58
59bool udl_probe_edid(struct udl_device *udl)
60{
61	u8 hdr[8];
62	int ret;
63
64	ret = udl_read_edid_block(udl, hdr, 0, sizeof(hdr));
65	if (ret)
66		return false;
67
68	/*
69	 * The adapter sends all-zeros if no monitor has been
70	 * connected. We consider anything else a connection.
71	 */
72	return !mem_is_zero(hdr, sizeof(hdr));
73}
74
75const struct drm_edid *udl_edid_read(struct drm_connector *connector)
76{
77	struct udl_device *udl = to_udl(connector->dev);
78
79	return drm_edid_read_custom(connector, udl_read_edid_block, udl);
80}